feat: REQ filter validation

[frnandu]

Evaluating strfry as a NWC relay alternative implementation we need such validation of REQ filters

  filterValidation {
        ## Example: Strict NWC relay configuration (similar to Alby's relay)
        enabled = true
        maxFiltersPerReq = 3
        minFiltersPerReq = 1
        maxKindsPerFilter = 3
        allowedKinds = "13194,23194,23195,23196,23197"
        requireAuthorOrTag = true
    }
  

[dskvr]

@frnandu every one of these filter validations can be achieved with plugins.

[frnandu]

@frnandu everyone one of these filter validations can be achieved with plugins.

AFAIK plugins are only for event writing policies, not for REQuests filters.

[dskvr]

Ah, yeah, you're right 👍

[hoytech]

Thank you, and sorry I've let this sit for so long. The change looks reasonable to me, except for a couple minor things:

• The allowedKinds config string is parsed on every request, which is inefficient. We can make it parse only once per thread, per config file update in the same way as getServerInfoHttpResponse and the like.
• There is currently a merge conflict against master.

I will fix this and merge for the next release.

[hoytech]

Merged. Thank you!